DE102018219331A1 - Operating a brushless DC motor - Google Patents

Abstract

The invention relates to a motor control device (1) for a three-phase brushless DC motor (2). The motor control device (1) comprises a power converter (3) which has an electrical half bridge (3.1, 3.2, 3.3) with two electronic switches (H1, H2, H3, L1, L2, L3) for each phase of the brushless DC motor (2) , and an application-specific integrated circuit (4) for controlling the electronic switches (H1, H2, H3, L1, L2, L3) of the converter (3). The application-specific integrated circuit (4) can be controlled in normal operation by a programmable control unit (9), has a first interface (AAD) for receiving an error signal (5) that signals a malfunction, and is designed to convert the converter (3) according to To receive the error signal (5) independently of the programmable control unit (9) in a defined final operating state (High_Z).

Description

The invention relates to a motor control device and a method for operating a three-phase brushless DC motor.

Safety-relevant systems must be put into a safe operating state in the event of a dangerous malfunction. For example, the standard ISO 26262 specifies safety requirement levels ASIL (= automotive safety integrity level) for safety-relevant systems in motor vehicles.

In some applications with electronically controlled brushless DC motors, a safe system state is achieved, for example, by actively driving the brushless DC motor into a predetermined operating state, for example a decoupled state in the case of a transmission actuator. Alternatively, the system can be brought into a safe operating state by mechanical means, for example by decoupling by means of a spring, or with microcontroller support, which, however, in some cases considerably reduces the likelihood of operating states of high safety requirement levels in the event of malfunctions in the electronic drive control system.

WO 2014/173792 A2 discloses a method for operating a three-phase brushless DC motor with electronic commutation controlled by pulse width modulation in the event of a malfunction. After the malfunction has been signaled, the rotor of the brushless DC motor is rotated with a predetermined maximum number of commutation steps in a predetermined direction of motor rotation and the brushless DC motor is then put into a selected operating end state.

The invention is based on the object of specifying an improved motor control device and an improved method for safely operating a brushless DC motor in the event of a malfunction.

The object is achieved according to the invention by a motor control device with the features of claim 1 and a method with the features of claim 6.

Advantageous embodiments of the invention are the subject of the dependent claims.

A motor control device according to the invention for a three-phase brushless DC motor comprises a converter which has an electrical half-bridge with two electronic switches for each phase of the brushless DC motor, and an application-specific integrated circuit for controlling the electronic switches of the converter. The application-specific integrated circuit can be controlled in normal operation by a programmable control unit, has a first interface for receiving an error signal signaling a malfunction and is designed to set the converter into a defined final operating state independently of the programmable control unit after receipt of the error signal.

The motor control device according to the invention enables a brushless DC motor to be put into a safe operating state in a safety-relevant malfunction without the support of a programmable control unit and controlled directly by an application-specific integrated circuit controlling the electronic switches of the converter, which is defined by a final operating state of the converter. In particular, this prevents the safe operating state from being prevented by errors in the programmable control unit, such as undesirable bit flips.

In one embodiment of the invention, the application-specific integrated circuit has a brake bit register for setting a brake bit and a count register for storing a count value for commutations changing for the switching state of the converter, and is designed to be used in the event that the brake bit is set when the error signal is received, immediately put the converter into the final operating state if the count is greater than zero, and put the converter into a braking mode for a defined braking period for braking the brushless DC motor if the count value is zero before the converter is brought into the final operating state.

The aforementioned embodiment of the invention enables the brushless DC motor to be braked in a controlled manner before the motor is put into the safe operating state, provided that braking is provided by setting the braking bit and there are no rotations in the motor provided by the counting value of the counting register.

In a further embodiment of the invention, the application-specific integrated circuit also has a second interface for receiving at least one sensor signal indicating a rotor position of a rotor of the brushless DC motor and is designed in the event that the brake bit is not set when the error signal is received and the Count value is greater than zero, before switching the converter into the final operating state, the switching state of the To change the converter by at least one commutation and after each commutation to check whether the commutation has caused a change in the rotor position of the rotor, and to decrement the count value in the case of a change in the rotor position by one until the count value is zero.

The aforementioned embodiment of the invention enables the motor to be rotated according to the count value of the count register before the motor is put into the safe operating state.

In a further embodiment of the invention, the application-specific integrated circuit has a timer and is designed to start the timer after receiving the error signal and to set the converter into the final operating state after a defined period of time has elapsed since the timer was started.

The aforementioned embodiment of the invention enables the motor to be put into the safe operating state at the latest after the period of time has elapsed, in particular also when, for example, the rotor of the brushless DC motor is blocked and therefore cannot be rotated further, and thus an execution specified by the count value of the count register is carried out Number of rotor rotations cannot be realized.

In a further embodiment of the invention, all electronic switches are switched off in the operating end state of the converter. This enables the rotor of the brushless DC motor to run freely and thus enables the motor to operate safely.

In the method according to the invention for operating a three-phase brushless DC motor with a motor control device according to the invention, each phase of the brushless DC motor is connected to an electrical half-bridge of the converter, the electronic switches of the converter are controlled by the application-specific integrated circuit, and the application-specific integrated circuit is operated in a normal mode by controlled by a programmable control unit, and the converter is put into the defined final operating state by the application-specific integrated circuit after receipt of the error signal, independently of the programmable control unit.

In one embodiment of the method, the application-specific integrated circuit has a brake bit register for setting a brake bit and a count register for storing a count value for the commutations changing for the switching state of the converter, and in the event that the brake bit is set when the error signal is received, the application-specific integrated circuit, the converters are immediately put into the final operating state if the count is greater than zero, and the converter is put into a braking mode for braking the brushless DC motor for a defined braking period before the setting, if the count is zero.

In a further embodiment of the method, the application-specific integrated circuit has a second interface for receiving at least one sensor signal indicating a rotor position of a rotor of the brushless DC motor, and the application-specific integrated circuit is used in the event that the brake bit is not set when the error signal is received and the count value is greater than zero, the switching state of the converter is changed by at least one commutation before the converter is brought into the operating end state, and after each commutation it is checked whether the commutation has caused a change in the rotor position of the rotor, and the count value is in the case of a change in rotor position decremented by one until the count is zero.

In a further embodiment of the method, the application-specific integrated circuit has a timer and the application-specific integrated circuit starts the timer after receiving the error signal and the converter is put into the operating end state after a defined period of time has elapsed since the timer was started.

In a further embodiment of the method, all electronic switches are switched off in the operational end state of the converter.

The advantages of the method according to the invention and its refinements correspond to the advantages of an engine control device according to the invention and their refinements mentioned above and are therefore not repeated here.

Exemplary embodiments of the invention are explained in more detail below with reference to drawings.

• 1 ein Blockdiagramm einer Motorsteuerungsvorrichtung für einen bürstenlosen Gleichstrommotor,
• 2 ein Ablaufdiagramm eines Verfahrens zum Betreiben eines bürstenlosen Gleichstrommotors in einem Fehlerfall.

In it show:

• 1 1 is a block diagram of a motor control device for a brushless DC motor.
• 2nd a flowchart of a method for operating a brushless DC motor in the event of a fault.

1 Figure 4 shows a block diagram of an engine control device 1 for a three-phase brushless DC motor 2nd .

The engine control device 1 includes a power converter 3rd for each phase of the brushless DC motor 2nd an electric half bridge 3.1 , 3.2 , 3.3 having. Every half bridge 3.1 , 3.2 , 3.3 has a first electronic switch H1 , H2 , H3 , a second electronic switch L1 , L2 , L3 and one with the respective phase of the brushless DC motor 2nd connected bridge branch. The first electronic switches H1 , H2 , H3 are with a positive pole of a voltage supply of the converter 3rd connected. The second electronic switches L1 , L2 , L3 are with a negative pole of the power supply of the converter 3rd connected. The electronic switches H1 , H2 , H3 , L1 , L2 , L3 are each formed, for example, as a MOSFET (metal oxide semiconductor field effect transistor) or alternatively as an IGBT (bipolar transistor with an insulated gate electrode).

The engine control device further comprises 1 an application-specific integrated circuit 4th to control the electronic switches H1 , H2 , H3 , L1 , L2 , L3 . The application-specific integrated circuit 4th has a first interface AAD to receive an error signal 5 to signal a safety-relevant malfunction, a second interface HALLx for receiving at least one rotor position of the rotor of the brushless DC motor 2nd indicating sensor signal 6 , for example at least one Hall sensor signal, and at least one further interface 7 for receiving engine control signals 8th on. The engine control signals 8th are controlled by a programmable control unit 9 generated by the application-specific integrated circuit 4th is controlled in an error-free normal operation. The engine control signals 8th are, for example, pulse width modulation signals for commutation of the electronic switches controlled by pulse width modulation H1 , H2 , H3 , L1 , L2 , L3 .

The application-specific integrated circuit 4th is designed to power the converter 3rd after receiving the error signal 5 independent of the programmable control unit 9 in a defined final operating state High_Z to put in which all electronic switches H1 , H2 , H3 , L1 , L2 , L3 be switched off and the one freewheeling state of the brushless DC motor 2nd causes. The application-specific integrated circuit points to this 4th an error handler 10th on receiving the error signal 5 is activated and its mode of operation is based on 2nd is described in more detail. Furthermore, the application-specific integrated circuit 4th a counting register 11 to save a count value AAD_Step_cnt for the switching status of the converter 3rd changing commutations, a brake bit register 12th for setting a brake bit AAD_Brake and a timer 13 on.

2nd shows a flowchart of a method with method steps S1 to S9 to operate the brushless DC motor 2nd after receiving the error signal 5 .

In a first step S1 becomes the error handler 10th activated and processing by the programmable control unit 9 generated engine control signals 8th is suspended. The following process steps S2 to S9 are from the Error Handler 10th independent of the programmable control unit 9 controlled. After the first step S1 become a second process step S2 and a ninth step S9 executed.

In the second step S2 becomes the brake bit register 12th read. If the brake bit AAD_Brake is set, that is if AAD_Brake = 1, the method with a third step S3 continued. Otherwise, that is if AAD_Brake = 0, the method is carried out with a fourth method step S4 continued.

In the third step S3 it is checked whether the count value AAD_Step_cnt Is zero. If this is the case, the process goes to a fifth step S5 continued. Otherwise, the process with a sixth step S6 continued.

In the fifth step S5 becomes the power converter 3rd for a defined braking period in a braking mode for braking the brushless DC motor 2nd transferred. Normally all second electronic switches are in braking mode L1 , L2 , L3 turned on and all the first electronic switches H1 , H2 , H3 switched off and in the exceptional case of a short circuit between the first electronic switches H1 , H2 , H3 and the phases of the brushless DC motor 2nd all first electronic switches H1 , H2 , H3 turned on and all second electronic switches L1 , L2 , L3 switched off. After the fifth step S5 becomes the sixth step S6 executed.

In the sixth step S6 the converter is in the final operating state High_Z transferred.

In the fourth step S4 it is also checked whether the count value AAD_Step_cnt Is zero. If so, the process continues with the sixth step S6 continued. Otherwise, the process with a seventh step S7 continued.

In the seventh step S7 becomes the switching state of the converter 3rd changed by a commutation and after the commutation it is checked whether the commutation has caused a change in the rotor position of the rotor. In the event of a change in the rotor position, an eighth process step S8 executed.

In the eighth step S8 becomes the count value AAD_Step_cnt Decremented by one. After the eighth step S8 becomes the seventh step S7 executed.

In the ninth step S9 becomes the timer 12th started. After a defined period of time has elapsed since the timer started 12th becomes the sixth step S6 executed, that is, the power converter 3rd is in the final operating state after the period High_Z if he is not yet in the final operating state High_Z located. In this way it is achieved that the converter 3rd at the latest after the end of the period in the operating end state High_Z is shifted, especially when the eighth step S8 is not executed, for example because the rotor of the brushless DC motor 2nd blocked and therefore cannot be rotated further.

The embodiment of the invention described above can be modified and supplemented in various ways. In particular, it can affect the control of brushless DC motors in an obvious manner to those skilled in the art 2nd be modified with a different number of phases.

Reference symbol list

1

Motor control device

2nd

brushless DC motor

3rd

Power converter

3.1, 3.2, 3.3

Half bridge

4th

Control unit

5

Error signal

6

Sensor signal

7, AAD, HALLx

interface

8th

Engine control signal

9

Control unit

10th

Error handler

11

Counting register

12

Brake bit register

13

Timer

AAD_Brake

Brake bit

AAD_Step_cnt

Count value

High_Z

Final operating state

H1, H2, H3

first electronic switch

L1, L2, L3

second electronic switch

S1 to S9

Procedural step

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2014/173792 A2 [0004]

Claims (10)

Motor control device (1) for a three-phase brushless DC motor (2), comprising the motor control device (1) - A converter (3) which has an electrical half-bridge (3.1, 3.2, 3.3) with two electronic switches (H1, H2, H3, L1, L2, L3) for each phase of the brushless DC motor (2), and - An application-specific integrated circuit (4) for controlling the electronic switches (H1, H2, H3, L1, L2, L3) of the converter (3), wherein - The application-specific integrated circuit (4) can be controlled in normal operation by a programmable control unit (9), has a first interface (AAD) for receiving a malfunction signaling error signal (5) and is designed to convert the converter (3) after To receive the error signal (5) independently of the programmable control unit (9) in a defined final operating state (High_Z). Motor control device (1) after Claim 1 The application-specific integrated circuit (4) has a brake bit register (12) for setting a brake bit (AAD_Brake) and a count register (11) for storing a count value (AAD_Step_cnt) for the switching state of the converter (3) and is designed to do so, In the event that the brake bit (AAD_Brake) is set when the error signal (5) is received, the converter (3) is immediately put into the final operating state (High_Z) if the count value (AAD_Step_cnt) is greater than zero, and the converter ( 3) before the converter (3) is put into the operating end state (High_Z) for a defined braking time in a braking mode for braking the brushless DC motor (2) if the count value (AAD_Step_cnt) is zero. Motor control device (1) after Claim 2 , The application-specific integrated circuit (4) has a second interface (HALLx) for receiving at least one sensor signal (6) indicating a rotor position of a rotor of the brushless DC motor (2) and is designed in the event that when the error signal ( 5) the brake bit (AAD_Brake) is not set and the count value (AAD_Step_cnt) is greater than zero, before switching the converter (3) to the final operating state (High_Z) to change the switching state of the converter (3) by at least one commutation and after check each commutation whether the commutation has caused a change in the rotor position of the rotor, and decrement the count value (AAD_Step_cnt) by one in the event of a change in the rotor position until the count value (AAD_Step_cnt) is zero. Motor control device (1) according to one of the preceding claims, wherein the application-specific integrated circuit (4) has a timer (13) and is designed to start the timer (13) after receipt of the error signal (5) and the converter (3) after a defined period of time since the start of the timer (13) in the final operating state (High_Z). Motor control device (1) according to one of the preceding claims, wherein in the operating end state (High_Z) of the converter (3) all electronic switches (H1, H2, H3, L1, L2, L3) are switched off. Method for operating a three-phase brushless DC motor (2) with a motor control device (1) designed according to one of the preceding claims, wherein - Each phase of the brushless DC motor (2) is connected to an electrical half bridge (3.1, 3.2, 3.3) of the converter (3), - The electronic switches (H1, H2, H3, L1, L2, L3) of the converter (3) are controlled with the application-specific integrated circuit (4), - The application-specific integrated circuit (4) is controlled in normal operation by a programmable control unit (9), and - The converter (3) from the application-specific integrated circuit (4) after receiving the error signal (5) is set independently of the programmable control unit (9) in the defined final operating state (High_Z). Procedure according to Claim 6 , wherein the application-specific integrated circuit (4) has a brake bit register (12) for setting a brake bit (AAD_Brake) and a count register (11) for storing a count value (AAD_Step_cnt) for the switching state of the converter (3), and in the case that the brake bit (AAD_Brake) is set when the error signal (5) is received, the application-specific integrated circuit (4) immediately switches the converter (3) to the final operating state (High_Z) if the count value (AAD_Step_cnt) is greater than zero and the converter (3) is put into a braking mode for braking the brushless DC motor (2) for a defined braking time before the converter (3) is in the operating end state (High_Z) when the count value (AAD_Step_cnt) is zero. Procedure according to Claim 7 , wherein the application-specific integrated circuit (4) has a second interface (HALLx) for receiving at least one sensor signal (6) indicating a rotor position of a rotor of the brushless DC motor (2), and of which application-specific integrated circuit (4) in the event that when the error signal (5) is received, the brake bit (AAD_Brake) is not set and the count value (AAD_Step_cnt) is greater than zero, before the converter (3) is put into the final operating state (High_Z ) the switching state of the converter (3) is changed by at least one commutation and after each commutation it is checked whether the commutation has caused a change in the rotor position of the rotor, and the count value (AAD_Step_cnt) is decremented by one in the event of a change in the rotor position until the count value (AAD_Step_cnt) is zero. Procedure according to one of the Claims 6 to 8th The application-specific integrated circuit (4) has a timer (13), and the application-specific integrated circuit (4) starts the timer (13) after receiving the error signal (5) and the converter (3) after a defined period of time since the start of the timer (13) in the final operating state (High_Z) is set. Procedure according to one of the Claims 6 to 9 , In the final operating state (High_Z) of the converter (3) all electronic switches (H1, H2, H3, L1, L2, L3) are switched off.

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